| Luzon Energy Limited | London | 2017 |
| LVS Land Limited | Motherwell | 2022 |
| LX Exhibition & Event Services Limited | Blandford Forum | 2009 |
| Lyceum Kingpin 1 Limited | Bristol | 2015 |
| Lyceum Kingpin 2 Limited | Bristol | 2015 |
| Lyceum Kingpin 3 Limited | Bristol | 2015 |
| Lyceum Nala Limited | Bristol | 2015 |
| Lyceum Pumbaa Limited | Bristol | 2015 |
| Lyceum Radiate 1 Limited | Bristol | 2013 |
| Lyceum Radiate 2 Limited | Bristol | 2014 |
| Lyceum Simba Finco Limited | Gatwick | 2025 |
| Lyceum Simba Holdco Limited | Gatwick | 2025 |
| Lyceum Simba Limited | Bristol | 2015 |
| Lyceum Solar Finco Limited | London | 2024 |
| Lyceum Solar Limited | London | 2023 |
| Lyceum SPV 10 Limited | Bristol | 2011 |
| Lyceum SPV 105 Limited | Bristol | 2013 |
| Lyceum SPV 106 Limited | Bristol | 2013 |
| Lyceum SPV 109 Limited | Bristol | 2013 |
| Lyceum SPV 115 Limited | Bristol | 2013 |
| Lyceum SPV 123 Limited | Bristol | 2013 |
| Lyceum SPV 135 Limited | Bristol | 2013 |
| Lyceum SPV 143 Limited | Bristol | 2013 |
| Lyceum SPV 160 Limited | Bristol | 2014 |
| Lyceum SPV 169 Limited | Bristol | 2014 |
| Lyceum SPV 170 Limited | Bristol | 2014 |
| Lyceum SPV 180 Limited | Bristol | 2014 |
| Lyceum SPV 20 Limited | Bristol | 2011 |
| Lyceum SPV 200 Limited | Bristol | 2014 |
| Lyceum SPV 224 Limited | Bristol | 2015 |
| Lyceum SPV 26 Limited | Bristol | 2011 |
| Lyceum SPV 32 Limited | Bristol | 2011 |
| Lyceum SPV 39 Limited | Bristol | 2011 |
| Lyceum SPV 40 Limited | Bristol | 2011 |
| Lyceum SPV 42 Limited | Bristol | 2012 |
| Lyceum SPV 44 Limited | Bristol | 2012 |
| Lyceum SPV 49 Limited | Bristol | 2012 |
| Lyceum SPV 5 Limited | Bristol | 2011 |
| Lyceum SPV 50 Limited | Bristol | 2012 |
| Lyceum SPV 54 Limited | Bristol | 2012 |
| Lyceum SPV 69 Limited | Bristol | 2012 |
| Lyceum SPV 74 Limited | Bristol | 2012 |
| Lyceum SPV 76 Limited | Bristol | 2012 |
| Lyceum SPV 79 Limited | Bristol | 2012 |
| Lyceum SPV 8 Limited | Bristol | 2011 |
| Lyceum Timon Limited | Bristol | 2015 |
| Lydney Engineering Co. Limited | Lydney | 1969 |
| Lyford Renewables Limited | London | 2014 |
| Lyford Renewables Solar Limited | London | 2020 |
| Lynch GAS Services Ltd | Eastcote | 2015 |
| Lynch Knoll Wind Park Limited | Stroud | 1995 |
| Lyndon Energy Limited | Mitcham | 2011 |
| Lynn Wind Farm Limited | Grimsby | 2001 |
| Lynt Farm Solar Limited | London | 2013 |
| Lyons Energy Supply Limited | Chorley | 2025 |
| Lyte Coatings Limited | Daventry | 2021 |
| Lythgoe's GAS Ltd | Peterborough | 2013 |
| Lythmore Solar Farm Limited | Edinburgh | 2023 |
| M & a Systems Ltd | Rochdale | 2012 |
| M & G Energy Limited | Newark | 2014 |
| M & G Equipment Limited | Wickham Bishops | 2015 |
| M & L Mechanical Limited | Peterborough | 2019 |
| M & M Power Limited | Leominster | 2013 |
| M & W Tromans Ltd | Newcastle Emlyn | 2015 |
| M 4 Energy Limited | Forfar | 2013 |
| M and M Electrical Services Ltd | Eastbourne | 2021 |
| M B Crewing Services Ltd | Great Yarmouth | 2015 |
| M Donnelly Electrical Ltd | Co Tyrone | 1999 |
| M F Ducting Ltd | Gloucester | 2015 |
| M G Electrics (N.E.) Limited | Spennymoor | 2010 |
| M G Electrics (UK) Ltd | County Durham | 2004 |
| M H Air Conditioning Limited | Stevenage | 2022 |
| M H Ventilation Ltd | Rochester | 2023 |
| M L Renewable Energy Ltd | Cross | 2014 |
| M S C Electric Ltd | London | 2017 |
| M S Cunningham Ltd | Harrogate | 2012 |
| M Sweeney Renewables Ltd | Thornaby | 2023 |
| M Telfer Electrical Services Ltd | Carluke | 2021 |
| M Thompson Bolting Solutions Ltd | Ashington | 2025 |
| M Wright Utilities Limited | Chelmsford | 2017 |
| M&D Construct Ltd | Barking | 2016 |
| M&E Dynamics Limited | Warrington | 2019 |
| M&F House Ltd | Whitstable | 2013 |
| M&M Heating & Plumbing Services Ltd. | Merthyr Tydfil | 2015 |
| M-J Ductwork Ltd | Rowley Regis | 2019 |
| M. R Cooling Ltd | Dereham | 2025 |
| M. T. Elec Ltd | Burnley | 2017 |
| M.A Holdings Surrey Ltd | Chertsey | 2019 |
| M.A.C.S Cool Limited | Goole | 2015 |
| M.A.L.D. Energy Ltd | Carmarthen | 2014 |
| M.A.S GAS Services Ltd | Arbroath | 2022 |
| M.C Young Engineering Ltd | Barnsley | 2019 |
| M.C.S.Ambler Limited | Thornton-Cleveleys | 2022 |
| M.D.Catharina Electrical Ltd | Croydon | 2022 |
| M.E.G Hydro Co Limited | Kilmarnock | 2014 |
| M.E.I.C Electrical Limited | Tamworth | 2010 |
| M.G. Electrical and Plumbing Ltd | Nottingham | 2015 |
| M.I.H. Tyne Tees (Belfast) Limited | Killingworth | 1995 |
| M.J. & S.C. Collins Limited | Chelmsford | 2011 |
| M.J.Electrical.Sp. Ltd | London | 2016 |